RESUMO
To find new molecular targets for triple negative breast cancer (TNBC), we analyzed a large-scale drug screening dataset based on breast cancer subtypes. We discovered that BDP-9066, a specific MRCK inhibitor (MRCKi), may be an effective drug against TNBC. After confirming the efficacy and specificity of BDP-9066 against TNBC in vitro and in vivo, we further analyzed the underlying mechanism of specific activity of BDP-9066 against TNBC. Comparing the transcriptome of BDP-9066-sensitive and -resistant cells, the activation of the focal adhesion and YAP/TAZ pathway were found to play an important role in the sensitive cells. Furthermore, YAP/TAZ is indeed repressed by BDP-9066 in the sensitive cells, and active form of YAP suppresses the effects of BDP-9066. YAP/TAZ expression and activity are high in TNBC, especially the Claudin-low subtype, consistent with the expression of focal adhesion-related genes. Interestingly, NF-κB functions downstream of YAP/TAZ in TNBC cells and is suppressed by BDP-9066. Furthermore, the PI3 kinase pathway adversely affected the effects of BDP-9066 and that alpelisib, a PI3 kinase inhibitor, synergistically increased the effects of BDP-9066, in PIK3CA mutant TNBC cells. Taken together, we have shown for the first time that MRCKi can be new drugs against TNBC, particularly the Claudin-low subtype.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Neoplasias de Mama Triplo Negativas , Humanos , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/metabolismo , Proteínas de Sinalização YAP , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Claudinas/genética , Claudinas/metabolismo , Linhagem Celular TumoralRESUMO
Yes-associated protein (YAP) is a transcription co-regulator downstream of the Hippo pathway, and plays a critical role in cancer. Although YAP regulation in the canonical Hippo pathway is well established, the Hippo-independent regulation of YAP is not well explored. Here, we showed the possible new mechanism of YAP regulation by the receptor tyrosine kinase Axl. Co-immunoprecipitation and Western blot analysis demonstrated the interaction between YAP and Axl, which was enhanced by Axl ligand Growth Arrest Specific 6 (GAS6) stimulation. Furthermore, we found that YAP is phosphorylated at tyrosine residues by GAS6 stimulation in vivo and Axl directly phosphorylates YAP in vitro. Axl overexpression or GAS6 stimulation increased YAP-mediated transcriptional activity, and YAP-mediated colony forming activity in soft agar was enhanced by co-expression of Axl. In EGFR tyrosine kinase inhibitor (TKI)-sensitive lung cancer cells, YAP protein was downregulated in response to TKI treatment, while overexpression of YAP attenuated TKI sensitivity, suggesting that YAP is a key determinant of TKI response. Moreover Axl overexpression reversed TKI-induced YAP downregulation and induced TKI-resistance, which was reversed by YAP knockdown, further supporting the notion that YAP functions downstream of Axl. Together, these findings suggest a novel role of YAP in Axl-mediated TKI resistance.
